Centro de Edafología y Biología Aplicada del Segura, Consejo Superior de Investigaciones Científicas (CEBAS-CSIC), 30100 Murcia, Spain.
Department of Molecular Physiology, Heinrich Heine University of Düsseldorf, 40225 Düsseldorf, Germany.
Int J Mol Sci. 2022 Oct 19;23(20):12503. doi: 10.3390/ijms232012503.
Most plant viruses lack the 5'-cap and 3'-poly(A) structures, which are common in their host mRNAs, and are crucial for translation initiation. Thus, alternative translation initiation mechanisms were identified for viral mRNAs, one of these being controlled by an RNA element in their 3'-ends that is able to enhance mRNA cap-independent translation (3'-CITE). The 3'-CITEs are modular and transferable RNA elements. In the case of poleroviruses, the mechanism of translation initiation of their RNAs in the host cell is still unclear; thus, it was studied for one of its members, cucurbit aphid-borne yellows virus (CABYV). We determined that efficient CABYV RNA translation requires the presence of a 3'-CITE in its 3'-UTR. We showed that this 3'-CITE requires the presence of the 5'-UTR for its eIF4E-independent activity. Efficient virus multiplication depended on 3'-CITE activity. In CABYV isolates belonging to the three phylogenetic groups identified so far, the 3'-CITEs differ, and recombination prediction analyses suggest that these 3'-CITEs have been acquired through recombination with an unknown donor. Since these isolates have evolved in different geographical regions, this may suggest that their respective 3'-CITEs are possibly better adapted to each region. We propose that translation of other polerovirus genomes may also be 3'-CITE-dependent.
大多数植物病毒缺乏 5'帽和 3'poly(A)结构，这些结构在其宿主 mRNA 中很常见，对于翻译起始至关重要。因此，人们确定了病毒 mRNA 的替代翻译起始机制，其中一种机制受其 3'末端的 RNA 元件控制，该元件能够增强 mRNA 帽非依赖性翻译（3'-CITE）。3'-CITE 是模块化和可转移的 RNA 元件。在多面体病毒的情况下，其 RNA 在宿主细胞中的翻译起始机制尚不清楚；因此，对其成员之一——葫芦科蚜虫传播的黄花病毒（CABYV）进行了研究。我们确定了有效的 CABYV RNA 翻译需要其 3'-UTR 中的 3'-CITE。我们表明，该 3'-CITE 需要 5'-UTR 的存在才能发挥其 eIF4E 非依赖性活性。有效的病毒繁殖依赖于 3'-CITE 活性。在迄今为止确定的三个系统发育组的 CABYV 分离株中，3'-CITE 不同，重组预测分析表明这些 3'-CITE 是通过与未知供体的重组获得的。由于这些分离株在不同的地理区域进化，这可能表明它们各自的 3'-CITE 可能更适应各自的区域。我们提出其他多面体病毒基因组的翻译也可能依赖于 3'-CITE。
